This study is the first part of the development of improved micro pin fin heat sink (MPFHS) for the thermal management of modern microprocessor chip cooling. In the current numerical study, a new fluid flow distribution scheme for MPFHS has been proposed for triumphing over surface temperature nonuniformity problem—one of the most critical issues interfering with the thermal management of modern microprocessors chip cooling. It is established that fluid, if supplied from the confronting sides (front/side directions) of the MPFHS, helps in mitigating temperature nonuniformity and intensifies heat transfer rate. Fluid starts enjoying following paybacks on account of proposed change: the benefits of the developing flow even in adverse temperature zones of the conventional design, enriched secondary channels fluid flow, and rigorous mixing of the cooling fluid between the primary and the secondary channels. Two front facing multi-inlet designs (MPFHSMI,F and MPFHSMI,FH) and one side facing multi-inlet design (MPFHSMI,SH) are conceptualized and compared with the conventional design MPFHSCD. Base surface temperature nonuniformity reduces 7.6 °C, 24 °C, and 7.4 °C by the MPFHSMI,F, MPFHSMI,FH, and MPFHSMI,SH designs, respectively. Average Nusselt number for the cases MPFHSMI,F, MPFHSMI,FH, and MPFHSMI,SH is found 26.7%, 52.3%, and 70.9% higher than the conventional design of MPFHS. Overall thermal performance factor of one design MPFHSMI,FH is found 1.66 at the applied heat flux of 125 W/cm2.